1. Field of the Invention
The invention relates to a method for manufacturing a woven zipper half, wherein a woven ribbon is produced of warp threads and of at least one weft thread, wherein the weft thread is picked in the form of double pick loops, wherein a wound closing member row is produced whose member-forming windings have interlocking heads at their one end and winding reversing portions at their other end, wherein the closing member row is positioned on a woven strip, and wherein during weaving at least one knit thread is guided through the gap between the windings upwardly to the upper side of the closing member row and its loop heads are interlocked by crocheting, wherein the crocheted loop heads form a mesh or stitch structure which covers portions of the upper side of the closure member row and connects the closing member row with the woven strip. Accordingly, such a zipper half is comprised, on the one hand, of a closing member row and, on the other hand, of a woven ribbon which are connected to one another in a weaving-technological way. The woven ribbon is woven of warp threads and of at least one weft thread wherein the weft thread is picked in the form of double pick loops. The closing member row is comprised of a wound plastic monofilament thread whose closing member-forming windings have interlocking heads at their one end and winding reversal portions at their other end. During weaving the closing member row is laid on a woven strip.
2. Description of the Related Art
The interlocking between the woven strip and the closing member row is realized by a knit thread which during weaving is lifted out of the woven strip in the form of loops and guided through gaps between the windings of the member row to the upper side of the closing member row where its loop heads are then interlocked by crocheting. The crocheted stitch heads form a mesh or knit structure. While the woven strip is positioned at the underside of the closing member row, the knit structure covers the upper side of the closing member row.
In the known method of this kind (German patent document DE 24 34 978 A) interlacing threads are present in the woven strip produced beneath the closing member row. They form a shed and interlock with a uniform weft extending across the entire width of the woven ribbon. This weft is picked as double pick loops, wherein the picking is carried out from the edge of the woven ribbon which carries the closing member row. Accordingly, at the oppositely positioned edge of the ribbon the projecting loop heads of this double pick must be interlocked by crocheting with one another, for which purpose a separate hook needle is required. Accordingly, a crocheted ribbon edge results which impairs the pleasing appearance of the zipper half. During weaving of the ribbon the sections of the interlacing thread are lifted in loops out of the resulting woven strip and penetrate through the loops between the windings of the closing member row to the upper side. Here, the produced loop of the interlacing thread is interlocked by crocheting with a preceding, already produced loop of another interlacing thread. For this interlocking by crocheting process, a second hook needle is required. Portions of the interlacing thread thus form loop-shaped knit threads. As a result of the woven strip below the closing member row and of the crocheting of the loop heads at the upper side, interlocking of the closing member row with the woven strip results. Not only a catch fork which provides the loop formation but also a second hook needle is required for controlling the interlacing threads during weaving. In order for the catch fork of the correspondingly selected partial piece of a certain interlacing thread to be gripped, a precise control is required. This known method is complex and failure-prone.
It is an object of the present invention to provide a reliable method of the aforementioned kind in which the product has a clean selvedge without a crocheted edge even though a woven ribbon with double picking has been woven.
In accordance with the present invention, this is achieved in that underneath the closing member row additional warp threads are positioned and that the loop-shaped knit thread at the same time forms the double pick loops which during weaving are interlaced with the additional warp threads, and the knit thread generates the weft thread in the woven strip underneath the closing member row.
According to the invention, warp threads are positioned underneath the closing member row which in the finished product are positioned exclusively in the plane of the woven strip that has been produced beneath the closing member row and which are not interlocked by crocheting with one another. In the following these threads will be referred to as xe2x80x9cadditional warp threadsxe2x80x9d. The special feature of the invention is that the knit thread forms at the same time the weft thread in the woven strip and interlocks during weaving in the form of double pick loops with the additional warp threads present in the woven strip. When interlocking with the additional warp threads, the double pick loops are guided through the gaps between the windings of the closing member row and their loop heads are interlocked by crocheting on the upper side of the closing member row. This crocheting action of the double pick loops cover portions of the upper side of the closing member row. The double picking of the knit thread produces thus at the oppositely positioned edge of the woven strip a clean, stitch-free selvedge. The produced zipper half has an excellent visual appearance.
The hook needle for interlocking the double pick loops of the knit thread acting like a weft is the same hook needle which produces the cover of the closing member row at the upper side. In comparison to the prior art, two components have been eliminated, i.e., a catch fork and a second hook needle for the loop ends of the double picks. The picking of the knit thread is realized by the weft needle and this weft needle produces not only the weave interlocking with the additional warp threads in the woven strip beneath the closing member row but also forms at the same time the loops penetrating between the gaps of the windings of the closing member row which are then crocheted with one another at the upper side. In addition to the hook needle, only a single tool is thus required, i.e., the weft needle. This weft needle is not only a weft picking means for the knit thread in the woven strip but also the loop head forming means of the knit thread for the hook needle.
The interlocking by crocheting of the loop heads generated from the knit thread can be realized by a direct stitch-like interlacing. However, it is further suggested to perform this also indirectly. For this purpose, an auxiliary thread is provided which realizes the stitch-like interlocking. Moreover, such an auxiliary thread, in addition to the stitch formation between the loop heads of the knit thread, can also effect a separate stitch-like interlocking between the closing member row, on the one hand, and the woven strip positioned underneath, on the other hand. With such an additional auxiliary thread the interlocking between the closing member row and the woven strip positioned underneath is improved.
In most applications, in addition to the woven strip with the closing member row positioned thereon, a wide support ribbon is also desirable which extends as a projecting web adjacent to the closing member row. Such a support ribbon is provided, for example, for attaching the zipper half by sewing on a piece of clothing which is to be provided with a zipper. The excellent appearance of the zipper half according to the invention is improved in that such a support ribbon is comprised of support ribbon warp threads and of a support ribbon weft which itself is picked in the form of double pick loops into the support ribbon warp threads. The support ribbon double pick also produces loop heads which, according to the method of the invention, are arranged in the zone where the loops of the knit thread, picked into the neighboring woven strip, penetrate through the gaps between the windings of the closing member row. The loops of the knit thread secure thus the loop heads of the support ribbon double picks before they are interlocked in a stitch-like manner with one another at the upper side of the closing member row, as has been mentioned above. Also, at the free edge of the support ribbon a flawless selvedge results because within this selvedge the support ribbon double pick enters the shed which is provided by the support ribbon warp threads. The woven material of this product than has clean selvedges on both sides. This has previously not been possible in the prior art when employing doubled picks.
With the afore described measures, a hook needle, which would be otherwise required for the stitch formation of the loop heads of the support ribbon double pick loops, can be eliminated at the free selvedge of the support ribbon. The knit thread has a triple function for such a zipper half comprising a support ribbon. The first function is, as mentioned before, that the knit thread as a weft thread produces the woven strip underneath the closing member row. The second function is that the knit thread interlocks the closing member row with the woven strip underneath because it is at the same time the weft thread in this woven strip. The third function of the knit thread is to interlock the support ribbon with the woven strip.
According to the invention, portions of the closing member row are covered at the underside by the already mentioned woven strip. On the opposite side, the already mentioned stitch-like interlocking of the loop heads of one or more knit threads or auxiliary threads is provided. In addition, or as a supplement thereto, at the upper side of the closing member row additional warp threads can be provided which interlock with such knit threads and thus form a woven material at the upper side which covers the member row even better.
It is advantageous in the context of the method according to the invention to wind the closing member row during weaving of the woven strip and/or of the support ribbon of a plastic monofilament thread by weaving-technological means. The manufacture of the individual closing members and their aforementioned interlocking is carried out in conformity with the knit threads acting in the woven strip in the manner of a weft thread. The adjusted winding of the closing member row and the interlocking weaving of the individual closing members formed of these windings provides a precise interlocking of the closing member row with the woven strip.